Hitherto, for example, Patent Literature 1 below describes a fine particle measurement device that is provided with an optical filter divided into a plurality of areas on an optical path through which light emitted from a fine particle by light irradiation is guided to an optical detector. The optical filter includes a first area having a wavelength selectivity to block reflection light and an unnecessary scattered light component from the fine particle but transmit fluorescence, and a second area arranged at least around the above-mentioned area, having no wavelength selectivity thereby allowing transmission of a necessary scattered light component.